Hydrogen and chemical energy storage in gas hydrate at mild conditions

Hydrogen storage in clathrate hydrates is a promising approach for industry-scale utilizations. However, extreme operation conditions such as high pressure (about GPa) limit the development. In this work hydrogen hydrate phase equilibrium in addition of methane, tert-butyl alcohol (tBA), trichloromethane (CHCl₃) and 1,1-dichloro-1-fluoroethane (HCFC-141 b) are reported at 6 MPa–20 MPa and 274 K–286 K, which including 21 points in total. Mechanism studies using Raman spectroscopy show that tBA and H₂O form metastable hydrate cages via hydrogen bonds, then form stable sII hydrates with the help of CH₄. Hydrate-based hydrogen storage capacity in 5.6 mol%HCFC-141 b-water mixture could reach 46 V/V (0.36 wt%) at 273 K and 10 MPa. Combing with chemical energy of HCFC-141 b, this work achieved high capacity of hydrogen and chemical energy storage in gas hydrate at mild conditions. This study will provide guidance on hydrate-chemical hybrid hydrogen storage technology, and leads to the next generation of hybrid hydrate-based hydrogen technology in the future.